HEMAGGLUTINATING ACTIVITIES OF ORAL STRAINS OF STREPTOCOCCUS-MILLERI GROUP

Of a total 148 strains of Streptococcus milleri group, 66 agglutinated sheep erythrocytes. The haemagglutinating strains were confined to se rotypes g, h, i, j or were untypeable, and had no Lancefield group ant igens (A to G and K), all of which have been shown to belong to Strept ococcus intermedius. Cell surface hydrophobicity did not significantly diff er even between the agglutinating and non-agglutinating S. inter medius strains. The haemagglutinating activity of strain 0813-1 (serot ype i) was partially sensitive to heat (100-degrees-C, 30 min) or tryp sin (1 mg/ml, 30 min) treatment, but completely lost after the heat an d subsequent trypsin treatments. Only L-arginine, L-lysine (100 mM), m ucin, and fetuin (1 mg/ml) partially inhibited the haemagglutination w ith native bacterial cells but completely inhibited that with heated c ells, whereas none was inhibitory in the reaction with trypsin-treated cells. The results suggest that at least two haemagglutinins are invo lved in the agglutination of the S. intermedius strain and that the he at-stable but trypsin-sensitive haemagglutinin recognizes the receptor s on the erythrocyte surface which contain L-arginine and L-lysine at the reactive site.